BEIRUT, Lebanon — Kurdish militias regained full control of the northern Syrian town of Kobani on Monday, driving Islamic State militants out with the help of American-led airstrikes, Kurdish activists on the scene said.

The bitter three-month battle for the border town took on outsize symbolic significance as it unfolded within sight of the Turkish border. It became the most visible arena in the American-led coalition’s fight against the Islamic State, which has seized large areas of Syria and Iraq, and the militant group’s retreat dented the aura of invincibility it has sought to cultivate.

But even as the Kurds celebrated, some activists said clearing the town was no great victory, given that it took more than 700 airstrikes to do it — nearly three-quarters of all the coalition’s strikes in Syria so far — and that Kobani was a relatively minor border city with a prewar population of 45,000.

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Kurds in Diyarbakir, Turkey, performed a traditional dance during a rally after news that ISIS had been driven from Kobani.CreditIlyas Akengin/Agence France-Presse — Getty Images

Improved coordination between Kurdish ground forces and the American-led air campaign made it possible to eliminate the Islamic State’s foothold in the city, the activists said. But the battle illustrated something else as well, they said: the extremists’ ability and willingness to hold on for months in the face of punishing aerial attacks, even in territory with limited military importance.

Their tenacity in Kobani showed the emphasis the Islamic State places on projecting an image of courage and power to attract recruits, the activists noted. But in the end, they said, the group appeared to have made a tactical decision to withdraw from Kobani, while its fighters continue to hold several hundred villages in the region whose Kurdish residents have nearly all fled.

“This can’t be counted as an achievement,” Mustafa Ebdi, a Kurdish activist in the nearby Turkish town of Suruc, said in a telephone interview Monday, even as the sounds of celebratory Kurdish songs and chants could be heard in the background. “ISIS is the one who decided to retreat.”

The United States Central Command said on Monday that about 90 percent of Kobani was now controlled by anti-Islamic State forces.

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Islamic State fighters swept across the agricultural lands around Kobani over the summer, but their advance attracted little outside attention until they threatened Kobani itself, around the time the American-led coalition began hitting targets in Syria.

The group, also known as ISIS, steadily redeployed fighters to Kobani from other parts of Syria, apparently hoping to show it could win a pitched battle despite Western air power.

The defenders of the town, the Kurdish People’s Protection Committees, or Y.P.G., were initially outgunned, but they drew support from the international coalition as they made a stand within sight of the television cameras across the border in Turkey. That made it “morally very difficult,” as Secretary of State John Kerry put it, not to help the Kurds.

Initially, Turkey refused to allow Kurdish fighters to cross into Syria to join the defense of Kobani, but the Turks relented under pressure, allowing Kurdish pesh merga fighters from Iraq to join the fight.

Most recently, according to the United States military, the air campaign pounded Islamic State positions around the town with 17 strikes over the past 24 hours.

“This advance came as a result of improved coordination between the American-led coalition and the forces fighting in Kobani,” Asia Abdullah, a Kurdish official in Kobani, said by telephone on Monday. “ISIS is weaker now, and paralyzed, unable to advance, but this doesn’t exclude the possibility that they might regroup and attack again.”

She added that the streets of Kobani were scattered with the corpses of ISIS fighters, and residents were hurrying to dispose of them to avoid the spread of disease.

Kobani was not nearly as important to the Islamic State’s advance as Mosul in Iraq or Raqqa in Syria, both of which it succeeded in seizing. Still, capturing Kobani would have given the group control of another border crossing into Turkey and could have helped the group link noncontiguous areas it controls.

Supporters of the Islamic State claimed on social media that the withdrawal from Kobani was merely a decision to send its fighters to more important fronts.

Correction:Jan. 31, 2015

An article on Tuesday about an announcement by Kurdish activists that their militias had retaken full control of Kobani, Syria, three months after Islamic State militants seized it referred incorrectly to a Kurdish official who said the victory was the result of improved coordination between Kurdish fighters on the ground and the American-led coalition that has been pounding ISIS positions in Kobani from the air. The official, Asia Abdullah, is a woman.

Anne Barnard reported from Beirut, and Karam Shoumali from Istanbul. Reporting was contributed by Eric Schmitt from Washington, and Mohammad Ghannam from Beirut.

A version of this article appears in print on , on Page A8 of the New York edition with the headline: Kurd Militia Says ISIS Is Expelled From Kobani. Order Reprints | Today’s Paper | Subscribe